[PATCH 3/6] rtc-lib: Check tm_wday for validity in rtc_valid_tm()

[Andrey Smirnov]

RTC drivers rely on rtc_valid_tm() in order to make sure that no bogus
values from uninitialized HW registers get passed to the uppper layers.

A somewhat contrived way to reproduce this problem with DS1307 RTC
would be to do the following:

> rtc_write -b <bus> -a <addr> -r 3 0x00
> hwclock

Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
---
 drivers/rtc/rtc-lib.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
index 1b23458..83d8045 100644
--- a/drivers/rtc/rtc-lib.c
+++ b/drivers/rtc/rtc-lib.c
@@ -90,6 +90,8 @@ int rtc_valid_tm(struct rtc_time *tm)
 {
 	if (tm->tm_year < 70
 		|| ((unsigned)tm->tm_mon) >= 12
+		|| tm->tm_wday < 0
+		|| tm->tm_wday > 6
 		|| tm->tm_mday < 1
 		|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
 		|| ((unsigned)tm->tm_hour) >= 24
--
2.5.0